Tuning the Inorganic Core of a reduced NiGe Cluster.

Tetranuclear cores (M-E) of transition metals (M) and tetrylenes (E=Si, Ge, Sn) are key motifs in homogeneous and heterogeneous catalysis. They exhibit a continuum of M-M and E-E bonding within the inorganic core that leads to a variety of structures for which there are no specific synthetic methods. Herein, we report a series of highly reduced [NiGe] squares solely stabilized by bulky terphenyl (CH-2,6-Ar) ligands, for which we provide complementary and high-yielding syntheses.

Lewis Acid-Assisted C(sp)-C(sp) Reductive Elimination at Gold.

The phosphine-borane PrP(-CH)BFxyl (Fxyl = 3,5-(FC)CH) was found to promote the reductive elimination of ethane from [AuMe(μ-Cl)]. Nuclear magnetic resonance monitoring revealed the intermediate formation of the ()AuMeCl complex. Density functional theory calculations identified a zwitterionic path as the lowest energy profile, with an overall activation barrier more than 10 kcal/mol lower than without borane assistance.

Mechanistic Investigations on Hydrogenation, Isomerization and Hydrosilylation Reactions Mediated by a Germyl-Rhodium System.

We recently disclosed a dehydrogenative double C-H bond activation reaction in the unusual pincer-type rhodium-germyl complex [(Ar)ClGeRh] (Ar=CH-2,6-(CH-2,4,6-Me)). Herein we investigate the catalytic applications of this Rh/Ge system in several transformations, namely semihydrogenation of internal alkynes, -isomerization of olefins and hydrosilylation of alkynes. We have compared the activity and selectivity of this catalyst against other common rhodium precursors, as well as related sterically hindered rhodium complexes, being the one with the germyl fragment superior in terms of selectivity towards -isomers.

1,1-Phosphaboration of C[triple bond, length as m-dash]C and C[double bond, length as m-dash]C bonds at gold.

The phosphine-borane iPr2P(o-C6H4)BFXyl2 (Fxyl = 3,5-(F3C)2C6H3) was found to react with gold(i) alkynyl and vinyl complexes via an original 1,1-phosphaboration process. Zwitterionic complexes resulting from Au to B transmetallation have been authenticated as key intermediates. X-ray diffraction analyses show that the alkynyl-borate moiety remains pendant while the vinyl-borate is side-on coordinated to gold.

A catalytic fluoride-rebound mechanism for C(sp)-CF bond formation.

The biological properties of trifluoromethyl compounds have led to their ubiquity in pharmaceuticals, yet their chemical properties have made their preparation a substantial challenge, necessitating innovative chemical solutions. We report the serendipitous discovery of a borane-catalyzed formal C(sp)-CF reductive elimination from Au(III) that accesses these compounds by a distinct mechanism proceeding via fluoride abstraction, migratory insertion, and C-F reductive elimination to achieve a net C-C bond construction. The parent bis(trifluoromethyl)Au(III) complexes tolerate a surprising breadth of synthetic protocols, enabling the synthesis of complex organic derivatives without cleavage of the Au-C bond.